From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 8A2B921F289 for ; Thu, 7 May 2015 00:37:13 -0700 (PDT) Received: from u-089-csam313b.am5.uni-tuebingen.de ([134.2.89.14]) by mail.gmx.com (mrgmx001) with ESMTPSA (Nemesis) id 0MGS9o-1Z3TmZ1j28-00DCnp; Thu, 07 May 2015 09:37:03 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: Date: Thu, 7 May 2015 09:37:01 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <35DD15D0-EBC2-4C07-9902-7D9C196061DF@gmx.de> References: <1429722979.18561.112.camel@edumazet-glaptop2.roam.corp.google.com> <5537DA20.1090008@orange.com> <5537DE4D.8090100@orange.com> <553882D7.4020301@orange.com> <1429771718.22254.32.camel@edumazet-glaptop2.roam.corp.google.com> <6C0D04CF-53AA-4D18-A4E4-B746AF6487C7@gmx.de> <87wq123p5r.fsf@toke.dk> <2288B614-B415-4017-A842-76E8F5DFDE4C@gmx.de> <553B06CE.1050209@superduper.net> <14ceed3c818.27f7.e972a4f4d859b00521b2b659602cb2f9@superduper.net> <0C930D43-A05B-48E2-BC01-792CAA72CAD1@gmx.de> <5549A1B8.50005@superduper.net> To: Jonathan Morton X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:CWBVslpmx1BytHawty94bhZ/Ie1iO9Z4S/objTsnRETS/Yjq6Pj XqegDncghlOxW1w01PvoD5j9TTj0ehqAX6/erkNPX9l1e3SziqKejYRT008Bjq4Kc2a8Jct S2maUCwvdfQ2j2f8gaa5AJHWwATTNjysFucXWw2PqtDv6hm+k1WS1VB01+6ID1m0bywh1w5 8JeTLi+hbfrJg6gEp/L3A== X-UI-Out-Filterresults: notjunk:1; Cc: bloat Subject: Re: [Bloat] DSLReports Speed Test has latency measurement built-in X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 May 2015 07:37:14 -0000 Hi Jonathan, On May 7, 2015, at 09:18 , Jonathan Morton = wrote: > It may depend on the application's tolerance to packet loss. A packet = delayed further than the jitter buffer's tolerance counts as lost, so = *IF* jitter is randomly distributed, jitter can be traded off against = loss. For those purposes, standard deviation may be a valid metric. All valid, but I think that the diced latency is not a normal = distribution, it has a lower bound the min RTT caused by the =93speed of = light=94 (I simplify), but no real upper bound (I think we have examples = of several seconds), so standard deviation or confidence intervals might = not be applicable (at least not formally). Best Regards Sebastian >=20 > However the more common characteristic is that delay is sometimes low = (link idle) and sometimes high (buffer full) and rarely in between. In = other words, delay samples are not statistically independent; loss due = to jitter is bursty, and real-time applications like VoIP can't cope = with that. For that reason, and due to your low temporal sampling rate, = you should take the peak delay observed under load and compare it to the = average during idle. >=20 > - Jonathan Morton > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat